This project is concerned with an investigation of brain mechanisms involved in species-typical prosematic (rudimentary signaling) communication. Observations are made on the effects of brain lesions on a highly predictable mirror display of one variety of squirrel monkeys (Saimiri sciureus). In an attempt to differentiate tegmental structures crucial for the display, a means is being sought for selectively destroying cellular elements without damage to fibers of passage. The present report describes the effects of applying puromycin and deferoxamine mesylate (a chelating agent for iron) at sites in the tegmentum.